Former Australia cricket head coach Justin Langer has backed spin guru Nathan Lyon for a series-defining performance in this Ashes series, detailing his importance to the Aussies.

While England batter Harry Brook has declared he wants to "take (Lyon) on", Langer doesn't believe it is an easy feat coming up against Lyon, who took nine wickets in the 2019 Ashes Test at Edgbaston. Four years later, he is capable of replicating that effort.

"England don't have a world-class spinner. That's no disrespect to Moeen (Ali). He's a good offie, but he's not Nathan Lyon," Langer told The Telegraph.

"I never realised until I started coaching Australia how good a bowler Nathan Lyon is. He's a very, very good bowler. Hard to get away, and incredibly important to Australia.

"Not only does he take wickets, but he bowls a lot of overs and traditionally holds up one end."

Lyon had another standout performance in Australia's World Test Championship Final triumph, notching four wickets in the second innings.

"You hear 'they are just going to smash Nathan Lyon,'" Langer continued.

"But, I was watching this week and Rohit Sharma, Shubman Gill, Virat Kohli. And I'm going, it's not that easy to do. I think he could be the difference in the series."

Langer stepped down from the coaching role in controversial circumstances last year after he was only offered a six-month contract following the Ashes and T20 World Cup successes.

The Ashes will commence on Friday at Edgbaston at 8:00 PM (AEST).